From: Jeremy Webber (jeremyw_at_al.com.au)
Date: Fri Sep 01 2006 - 06:31:01 CEST
Message-Id: <553c2a7a2660726c2aceb57b49cdc0b7@al.com.au> From: Jeremy Webber <jeremyw@al.com.au> Date: Fri, 1 Sep 2006 14:31:01 +1000 Subject: Re: [suse-sles-e] where did all my memory go?
On 01/09/2006, at 12:58 PM, Peter Van Lone wrote:
> If I understand this correctly, there is only about 260 mb of memory
> "free".
>
> Does this mean ... only that much ram is available for new processes?
> Or, is there some "idle" process that has all of this ram?
>
Linux typically finds a use for any memory not required for running
programs. Mostly the otherwise unused memory is used for the
filesystem cache.
This is good as it ensures the memory does not go to waste. The
filesystem cache memory can be quickly reallocated to processes when
required.
Your system looks fine from the top listing you showed. If you were
short of memory then some of the swap would be used, as things stand
none of it is used.
You can find out more information with the 'vmstat' command. If you
consistently get high swap in and swap out readings, then you are short
of memory (or you have an application which is a memory hog). E.g.:
> vmstat 5
procs -----------memory---------- ---swap-- -----io---- --system--
----cpu----
r b swpd free buff cache si so bi bo in cs us
sy id wa
0 0 920 855764 0 2873260 0 0 1 0 1 1 4
1 95 0
0 0 920 855888 0 2873260 0 0 0 9 1029 110 2
0 98 0
0 0 920 855952 0 2873260 0 0 0 6 1019 89 0
0 100 0
The 'si' and 'so' columns give you swap in and swap outs per second.
Occasional non-zero figures are fine, but if you have consistent high
figures (> a few tens) you have problems. Look also at the I/O figures
and the I/O wait CPU figure, in case your system is I/O bound.
Remember the first line of output of 'vmstat' gives an average since
start up, so ignore it in your analysis.
HTH,
Jeremy
--
Jeremy Webber Senior Systems Engineer
Animal Logic Pty Ltd
Phone: +61 2 9383 4837 Fax: +61 2 9383 4801 Switch: +61 2 9383 4800
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